O2 ≤1ppm N2 ≤5ppm H2 ≤1ppm H20 ≤4ppm total carbon content ≤2ppm ... >>>

O2≤10ppm N2≤50ppm H2≤5ppm... >>>

O2≤4ppm N2≤15ppm H2≤2ppm... >>>

Ne ≤4vpm H2 ≤1vpm O2+Ar ≤1vpm ... >>>

Ne≤15vpm H2≤3vpm O2+Ar≤3vpm ... >>>